Previous inventions for impact resistant windows, storefronts and curtain walls focused on wind loads and impact requirements such as TAS201, TAS 202, TAS203 in the Florida Building Code or ASTM E 1886 and 1996. For hurricane protection, this performance correlates to Category 1, 2, and 3 hurricanes and there is no correlation to tornado wind load. Prior laminated glass products by DuPont Corporation include a ‘low haze’ feature that uses a plastic interlayer between glass layers as described in U.S. Pat. No. 7,214,433, U.S. Pat. Pub. No. 2005118445 and WO99/58334. DuPont refers to this interlayer as thermoplastic polymer or SentryGlas® Plus (SGP). Alternate interlayers were made from polyvinyl butyral. Glass using ‘thermoplastic polymer’ interlayers is referred, herein, as ‘laminated glass.’
The thermoplastic polymer interlayer used in prior applications included 0.09 inches, 0.1 inches, or 0.18 inches in thickness, providing some protection against wind load, and flying debris, as described in the previous paragraph. Early impact applications used solid plastic vision lites but these efforts were generally abandoned in favor of laminated glass. The current invention follows this trend of using laminated glass with thermoplastic polymer in lieu of solid plastic vision lites.
No prior art is known for an impact resistant glass window, storefront or curtain wall, able to withstand loads and impacts up to Category 5 (Saffir-Simpson scale) hurricanes (up to 225 mph USA wind) or EF5 (Enhanced Fujita scale) tornadoes (up to 250 mph USA wind) as described in ICC500 (see below). There are alternative impact resistant window, storefront or curtain walls with solid plastic vision lites but these plastics have the same drawbacks of yellowing and scratching found with the earliest plastic vision lites designed as impact resistant.
What is needed is a glass window system based on a laminated glass with a thermoplastic interlayer that will withstand wind loads and impacts up to Category 5 (Saffir-Simpson scale) hurricanes and/or EF5 (Enhanced Fujita scale) tornadoes with ICC500 performance requirements.